Piezoelectric ceramic electronic components are currently mounted in various electronic apparatuses, and for those piezoelectric ceramic electronic components, ceramic sintered bodies each primarily formed of a ceramic material have been widely used.
In addition, as a ceramic material used for a piezoelectric body, composite oxides (hereinafter referred to as “perovskite type compound”), such as lead titanate (hereinafter referred to as “PT”) and lead zirconate titanate (hereinafter referred to as “PZT”), each having a perovskite type crystal structure have been widely used.
With this type of ceramic sintered body, it has been known that when the orientation of the crystal is controlled, various types of characteristics, such as piezoelectric characteristics, are improved. In addition, as related techniques on oriented ceramics, for example, the following Patent Documents 1 to 3 have been known.
Patent Document 1 has proposed a piezoelectric element which includes a substrate having a pair of main surfaces facing each other, a lower electrode layer disposed on one main surface of the substrate, a piezoelectric layer disposed on the lower electrode layer, and an upper electrode layer disposed on the piezoelectric layer, and in this piezoelectric element, the lower electrode layer described above is formed of a lanthanum nickelate ceramic.
In this Patent Document 1, a lanthanum nickelate ceramic preferentially oriented in the (100) plane of a pseudo-cubic crystal system is used as the lower electrode layer, and a PZT ceramic preferentially oriented in the (001) plane is formed on the lower electrode using a liquid phase growth method.
In addition, Patent Document 2 has proposed a crystal-oriented ceramic in which the crystal is oriented in a predetermined crystal plane, and in this crystal-oriented ceramic, an element contained therein has a composition distribution in a direction orthogonal to the above crystal plane, and the degree of orientation is 25% or more by a Lotgering method.
In this Patent Document 2, the crystal-oriented ceramic is formed by using a TGG (Templated Grain Growth) method. That is, after anisotropically shaped particles (template material) oriented along the c-axis and non-oriented inorganic particles are mixed together, a ceramic molded body is formed by molding this mixture and is then fired, so that the crystal-oriented ceramic is formed.
In addition, Patent Document 3 has proposed a piezoelectric/electrostritive film element including a ceramic sintered substrate, an electrode, and a piezoelectric/electrostrictive body which is provided on the ceramic sintered substrate directly or indirectly with the electrode interposed therebetween, which contains no glass components, and which is oriented in a specific direction.
This Patent Document 3 has disclosed a piezoelectric/electrostritive film element in which the pseudo-cubic (100) axis is oriented along an electric field direction.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-251916 (for example, claims 1 to 14)
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2009-167071 (for example, claim 1 and paragraphs [0015] to [0022])
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2010-021512 (for example, claims 1 and 10)